Walter Jackson Freeman III, a neuroscientist and philosopher known for his pioneering work on how the brain generates our perception of the world, died Sunday, April 24, at his home in Berkeley. He was 89.

A professor emeritus of molecular and cell biology at the University of California, Berkeley, Freeman died from pulmonary fibrosis of unknown cause, an affliction that did not keep him from walking to campus every day until just a few months ago.

Freeman is considered one of the founders of the field of computational neuroscience, which uses mathematics and computers to understand brain dynamics and neural networks. He published nearly 500 research articles in his lifetime, in addition to popular books –Societies of Brains: A Study in the Neuroscience of Love and Hate (1995) and How Brains Make Up Their Minds (2001) – that brought the ideas of brain dynamics and chaos theory to lay audiences.

His studies led him to philosophize and write about the nature and origin of consciousness and perception, and the role of chaos in creativity and in allowing animal brains to respond flexibly to a constantly changing world. He proposed that the way brains work is compatible with the thinking of 13th- century philosopher Saint Thomas Aquinas about the unity of brain, body and mind, or soul.

“He argued that questions about mind and consciousness, often considered philosophical problems, could be addressed by experimental investigations of the collective properties of neurons,” said David Presti, a colleague and UC Berkeley neuroscientist.

Mind and body

At a time when many scientists thought that the various functions of brains – touch and vision, for example – could be explained by simple networks of neurons, like the circuit diagram of a computer, he proposed that the collective behavior of neurons stretching throughout the brain is responsible for perception. This self-organized behavior, he argued, means that the images we see in our minds are the collective activity of many neurons spread over the brain, not the activity of single neurons.

“Perception cannot be understood solely by examining properties of individual neurons,” he wrote in a 1991 Scientific American article. “We have found that perception depends on the simultaneous, cooperative activity of millions of neurons spread throughout expanses of the cortex.”

“The brain reaches out into the environment and sees something which is then interpreted according to its own past experience,” Freeman said in a 1991 interview. “First you look, then you see. The process of recognition begins from within.”

His insights were rooted in the study of smell in cats and rabbits, where he measured brain activity with electrodes inserted into the brain or electroencephalograms (EEGs) on the brain surface, and then modeled these recordings mathematically to understand how the animals perceived smell.

“He tackled the really big issue of how we can understand how millions of neurons in the cerebral cortex work together and profoundly influence one another to govern how brains operate – what he called ‘mass action’ – rather than focus on the much more tractable, though important, question of how individual neurons work and how they are connected together,” Presti said.

His book, Mass Action in the Nervous System (1975), was one of the first texts to use mathematics to describe brain dynamics. More recently, Freeman expanded concepts developed by studying the olfactory system to higher-order brain functions, such as memory and motor systems, according to Freeman’s former student Leslie Kay, now a professor of psychology at the University of Chicago. Freeman was even working with others to apply quantum field theory to understanding neural networks.

“A lot of his theories are starting to pop up again in new form in the scientific literature, without attribution, because his papers are extremely difficult and highly mathematical,” Kay said. “People are rediscovering things that Walter discovered years ago.”

“I used to say that Walter was about 50 years ahead of the rest of neuroscience,” Presti added. “I now believe that number has been reduced to 10 to 15 years.”

He trained many graduate students and postdoctoral scholars in his career, and influenced an uncountable number of scientists in the U.S. and across the globe.

“To his last breath, he was educating his students and listening to new interpretations of his work,” Kay said. “He was a demanding yet generous teacher and scholar, and believed strongly in educating others in the role of emergent neural states as the primary causal level in perception-action processes.”

A brainy family

Freeman was born on Jan. 30, 1927, in Washington, D.C., the son of physician Walter J. Freeman II, one of the foremost U.S. champions of lobotomies to treat mental illness, and the great-grandson of Civil War surgeon William Keen, the nation’s first brain surgeon. As an undergraduate he studied physics at the Massachusetts Institute of Technology, English and philosophy at the University of Chicago and electronics in the U.S. Naval Reserve. He never received an undergraduate degree, but entered Yale Medical School and graduated cum laude in 1954.

He was trained in research by John F. Fulton, who had studied with the famed British scientist Sir Charles Sherrington, who won the 1932 Nobel Prize for his work on neurons and synapses. Freeman did postdoctoral work in neuropsychiatry at UCLA and joined the UC Berkeley faculty in 1959. Between 1967 and 1972 he served as chair of the Department of Anatomy and Physiology, which later became part of the Department of Molecular and Cell Biology.

His honors include a Guggenheim fellowship, Titulaire de la Chaire Solvay at Universite Libre de Bruxelles, a MERIT award from the NIH, the Pioneer award from the IEEE Neural Networks Council, Spinoza Lecturer at the University of Amsterdam, a lifetime achievement award from the University of Salerno Medical School and the Helmholtz Lifetime Achievement Award from the International Neural Network Society, among many others. He was an honorary professor at Fudan University in Shanghai and Zhejiang University in Hangzhou.

Freeman pursued his personal life as vigorously and passionately as his work, said his daughter, Abigail Karin. “His colleagues, friends and family were thrown together in a chaotic tumbling collection of ideas, love and fellowship. He held these together with intentionality, turning this fellowship into a fabric of his own vision. His charismatic and rebellious spirit could infuriate, inspire and ignite those who crossed his path.”

He was a member and contributor to the Bay Area Rock Art Research Association, where he and his fellows hunted for petroglyphs in California, Mexico and remote enclaves around the world.

He was preceded in death by his wife, Doreliesje “Do” Freeman, and is survived by seven children – Luke, of Australia, and Abigail, Mathew, Walter IV, Rachael, Joran and Jennifer – five stepchildren – Mark, Tom, Kim, Rachel and Toni – his first wife, Maribelle Zechlin, and 18 grandchildren.